Deck 8: Producing Data- Experiments

Question 1

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three treatment groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in a diet and exercise program. Researchers observed the amount of weight lost five years after the study began. The response is:

A)the kind of program to which a subject was assigned.
B)the amount of weight lost five years after the study began.
C)gastric bypass surgery.
D)random assignment.

Answer 1

the amount of weight lost five years after the study began.

Question 2

Sickle-cell disease is a painful disorder of the red blood cells that, in the United States, affects mostly African Americans. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell disease, a study by the National Institutes of Health gave the drug to 150 sickle-cell sufferers and a placebo to another 150. Neither doctors nor patients were told who received the drug. The number of episodes of pain reported by each subject was recorded. This is an example of:

A)an observational study.
B)an experiment, but not a double-blind experiment.
C)a double-blind experiment.
D)a paired data experiment.

Answer 2

a double-blind experiment.

Question 3

A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse could be selected from a given pasture. The study is:

A)a randomized block design.
B)a matched pairs design.
C)a completely randomized design.
D)a comparative observational design.

Answer 3

a randomized block design.

Question 4

A placebo is an important element of many clinical trials because:

A)it serves as a control for the experiment.
B)it allows the researcher to adjust for the psychological effects of receiving medical attention.
C)the use of the placebo can help avoid confounding.
D)All of the answer options are correct.

Question 5

Apparently, according to some studies, men who drive expensive sports cars have lower blood pressure and fewer cardiovascular health problems. We can't conclude that driving expensive sports cars lowers blood pressure or improves cardiovascular health because the studies described are clearly:

A)experiments.
B)observational studies, not experiments-lurking variables may explain the association.
C)paired data experiments.
D)stratified experiments.

Question 6

A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse can be selected from a given pasture. After one year, the horses are given radiographs to determine if enteroliths are present in the gut. The response is:

A)the diet a horse is given.
B)the amount of feed a horse is given.
C)the number of enteroliths.
D)the presence or absence of enteroliths.

Question 7

The purpose of blocking is:

A)to arrange experimental units according to similarity.
B)to ensure that the results from an experiment are accurate.
C)to control the effects of an outside variable that is not of interest to the researchers.
D)All of the answer options are correct.

Question 8

A veterinarian is interested in studying the causes of enteroliths (stones that form in the gut of horses). An observational study comparing the diet of horses admitted to the veterinary hospital with enteroliths and the diet of horses admitted for other reasons does not allow causal conclusions to be drawn because:

A)an observational study can only establish correlations, unless the investigator is double blinded.
B)associations in observational studies can be confounded by lurking variables.
C)the study does not match horses.
D)All of the answer options are correct.

Question 9

A veterinarian is interested in studying the causes of enteroliths (stones that form in the gut of horses). In order to establish a causal relationship between diet and enteroliths, the veterinarian needs to:

A)use a double-blind observational study.
B)use a nonrandomized experimental design in which the examining veterinarian is blinded to the diet the horse is fed.
C)use a comparative randomized experiment.
D)use a survey questionnaire that is to be administered to all horse owners entering the veterinary hospital.

Question 10

A veterinarian interested in studying the causes of enteroliths (stones that form in the gut of horses) decided to compare the diets of horses with enteroliths and horses without that were admitted to the veterinary hospital. This study is an example of:

A)an experimental study.
B)a survey.
C)an observational study.
D)None of the answer options is correct.

Question 11

At a local health club, a researcher samples 75 people whose primary exercise is cardiovascular and 75 people whose primary exercise is strength training. The researcher's objective is to assess the affect of type of exercise on cholesterol. Each subject reported to a clinic to have his or her cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of the subject's type of exercise. This approach is:

A)an observational study.
B)an experiment, but not a double-blind experiment.
C)a double-blind experiment.
D)fundamentally flawed, because only a well-designed experiment with randomized assignment to treatments can be used to determine a cause-and-effect relationship.

Question 12

A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse could be selected from a given pasture. This study has:

A)one factor and three treatments.
B)one treatment and three factors.
C)three treatments and three factors.
D)one factor and one treatment.

Question 13

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a business class view one or the other price history on a computer. Some students see a steady price, whereas others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay. This is an example of:

A)a matched pairs experiment.
B)a two-factor design.
C)a randomized comparative experiment.
D)a randomized observational study.

Question 14

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a business class view one or the other price history on a computer. Some students see a steady price, whereas others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay. The response is:

A)the laundry detergent.
B)the eight business students.
C)the price the students would expect to pay.
D)the sale prices.

Question 15

A researcher studying the effect of price cuts on consumers' expectations makes up two different histories of the store price of a hypothetical brand of laundry detergent for the past year. Eight students in a business class view one or the other price history on a computer. Some students see a steady price, whereas others see regular sales that temporarily cut the price. Students are asked the price they would expect to pay. The experimental units are:

A)all business students at the college.
B)the eight business students who participated.
C)the business students who were in the fluctuating price group.
D)the price the students would expect to pay.

Question 16

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three treatment groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in a diet and exercise program. Researchers observed the amount of weight lost five years after the study began. This study uses the principles of:

A)randomization.
B)confounding.
C)blocking.
D)All of the answer options are correct.

Question 17

To investigate whether women are more likely than men to prefer Democratic candidates, a political scientist selects a large sample of registered voters, both men and women. She asks every voter whether they voted for the Republican or the Democratic candidate in the last election. This is:

A)an observational study.
B)a multistage sample.
C)a double-blind experiment.
D)a block design.

Question 18

Some researchers have noted that adolescents who spend a lot of time playing video or computer games are at greater risk for depression and violence. This is an example of:

A)a valid conclusion, because more time yields more aggression is a positive association.
B)an observational study with lurking variables that may explain the association.
C)a single-blind experiment, because the subjects knew they were playing games.
D)a paired data experiment, because we are studying both aggression and game playing.

Question 19

A veterinarian interested in studying the causes of enteroliths in horses suspects that a diet high in alfalfa may be a cause. The veterinarian decides to use the following design: identify 30 horses at high risk for enteroliths, and divide them into 10 groups of 3 horses. Some groups consist of horses in barn stalls, some groups consist of horses in outdoor paddocks, and some groups consist of horses in pastures. Within each group, one horse is randomly assigned to an alfalfa diet, one is assigned to a grass hay diet, and one horse is fed oat hay. When a horse is in a pasture, all the other horses in that pasture will also receive the diet of the study horse. Therefore, only one horse could be selected from a given pasture. The blocking is done:

A)to reduce the potentially confounding effect of comparing more than two treatments.
B)to reduce the potentially confounding effect that the type of housing may have.
C)to increase the treatment effects.
D)All of the answer options are correct.

Question 20

In order to investigate treatments for morbid obesity, obese subjects satisfying fairly strict requirements were randomly assigned to one of three treatment groups: (1) gastric bypass surgery, (2) participation in a diet and exercise program, or (3) both gastric bypass surgery and participation in a diet and exercise program. Researchers observed the amount of weight lost five years after the study began. This study has:

A)four factors.
B)three treatments.
C)two treatments.
D)None of the answer options is correct.

Question 21

In a study of human development, investigators showed two different types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One type of movie was shown at 8 A.M. (right after the children had breakfast) and the other type of movie was shown at 11 A.M. (right before the children were to have lunch). It was found that more crackers were eaten during the movie shown at 11 A.M. than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had different effects on appetite. The treatment in this experiment is:

A)the number of crackers eaten.
B)the different kinds of movies.
C)the time each movie was shown.
D)the bowls.

Question 22

A nutritionist has designed an intervention to motivate parents of preschool children to provide more fruits and vegetables to their children. To study the effectiveness of this intervention, the nutritionist will conduct an experiment in which half of the selected study participants will receive the intervention and the others will not. Study subjects will be recruited from families with children who receive medical care for their children through the university health center. One factor that must be accounted for is whether the family receives aid through the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), which provides funds for fruits and vegetables to the mothers. Which of the following experiments should the nutritionist use?

A)a completely randomized design
B)a matched design where children are matched on age and gender, and the WIC child does not get the intervention
C)a randomized matched pairs design where parents are matched on age, gender, and WIC program participation
D)a matched pairs observational study

Question 23

A study is conducted to investigate the effects of a new exercise program on lameness in race horses. A group of horses at a local race track is selected for the study. The horses are randomly assigned to two groups. Group 1 horses will train according to the new program for one month, rest for two weeks, and then train according to the old program for one month. Group 2 horses will have the order of the old and new programs reversed. Here, each horse serves as its own control. The two groups are necessary to avoid:

A)a carryover effect, since the order of treatment may influence the subject's response.
B)a placebo effect.
C)a double-blind effect.
D)a confounded effect.

Question 24

In a study of human development, investigators showed two different types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One type of movie was shown at 8 A.M. (right after the children had breakfast) and the other type of movie was shown at 11 A.M. (right before the children were to have lunch). It was found that more crackers were eaten during the movie shown at 11 A.M. than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had different effects on appetite. The response variable in this experiment is:

A)the number of crackers eaten.
B)the different types of movies.
C)the time each movie was shown.
D)the bowls.

Question 25

A researcher finds 1000 mildly overweight women who exercise regularly, have not had a heart attack, and are willing to participate in the study. She randomly assigns 500 of the women to take an appetite suppressant. The other 500 women are given a placebo. Both groups are followed for five years, and the amount of weight lost after this time is recorded. The factor in the experiment is:

A)the weight lost by women in the study.
B)the use of a control group taking a placebo.
C)the treatment taken by women in the study-appetite suppressant or placebo.
D)the length of the study.

Question 26

A study is done to assess the effects of a new medication on the resting heart rate of dogs. Two breeds will be used in the study because of the availability of experimental subjects, even though the researcher is not interested in the differences in the medication's effectiveness between breeds. What type of experimental design should be used?

A)no blinding; no blocking
B)no blinding; blocking on dog breed
C)double blind; no blocking
D)double blind; blocking on dog breed

Question 27

In a study of human development, investigators showed two different types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching both movies. One type of movie was shown at 8 A.M. (right after the children had breakfast) and the other type of movie was shown at 11 A.M. (right before the children were to have lunch). It was found that more crackers were eaten during the movie shown at 11 A.M. than during the movie shown at 8 A.M. The investigators concluded that the different types of movies had different effects on appetite. The results cannot be trusted because:

A)the study was not double blind-neither the investigators nor the children should have been aware of which type of movie was being shown.
B)the investigators were biased-they knew beforehand what the study would show.
C)the investigators should have used several bowls, with crackers randomly placed in each.
D)the time each movie was shown is a confounding variable.

Question 28

One hundred sixty people who suffer from painful diabetic neuropathy have volunteered to participate in a study. Eighty are selected at random and are given the drug gabapentin, which (although originally intended to prevent epileptic seizures) has properties that may make it useful to alleviate neuropathy. The remaining participants are given a placebo. A neurologist evaluates the symptoms of all volunteers after two months to determine if there has been substantial improvement in the severity of the symptoms. Does the use of volunteers make this study invalid?

A)Yes, because of volunteer bias.
B)Yes, because there is no way to determine the effect of the drug on people that do not have symptoms of neuropathy.
C)No, because the subjects are randomly assigned to treatment groups.
D)No, because blocking was used.

Question 29

One hundred sixty people who suffer from painful diabetic neuropathy have volunteered to participate in a study. Eighty are selected at random and are given the drug gabapentin, which (although originally intended to prevent epileptic seizures) has properties that may make it useful to alleviate neuropathy. The remaining participants are given a placebo. A neurologist evaluates the symptoms of all volunteers after two months to determine if there has been substantial improvement in the severity of the symptoms. Suppose the volunteers were first divided into men and women, and then half of the men were randomly assigned to the new drug and half of the women were assigned to the new drug. The remaining volunteers received the placebo. This would be an example of:

A)replication.
B)confounding-the effects of gender will be mixed up with the effects of the drug.
C)a block design.
D)a matched pairs design.

Question 30

Researchers have noted that children who learn to play a musical instrument through taking lessons have higher average SAT scores, higher average GPAs, and higher average class ranks. The various measures of academic success described are examples of:

A)explanatory variables.
B)response variables.
C)confounding variables.
D)None of the answer options is correct.

Question 31

A researcher finds 1000 mildly overweight women who exercise regularly, have not had a heart attack, and are willing to participate in the study. She randomly assigns 500 of the women to take an appetite suppressant. The other 500 women are given a placebo. Both groups are followed for five years, and the amount of weight lost after this time is recorded. The response variable in this experiment is:

A)the amount of weight lost.
B)the proportion of women in each group that stayed in the study.
C)whether the women exercised.
D)the age of the women.

Question 32

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. Before the start of the class, each student is asked about the number of hours slept the previous night. Each student's eye movement is then tracked throughout the lecture. The amount of time is recorded whenever the student is not focused on either the instructor or taking notes. The class is offered at 11 A.M. A potential confounder is given by the number of classes a student has prior to calculus because:

A)the larger the number of classes earlier in the day, the earlier the student has to get up and therefore sleeps less.
B)the larger the number of classes earlier in the day, the more a student has to prepare and likely stays up late.
C)many classes earlier in the day will leave a student tired just from having to stay focused for several hours.
D)All of the answer options are correct.

Question 33

Randomly assigning all subjects to treatment groups is called:

A)a completely randomized design.
B)a randomized complete block design.
C)a randomized comparative experiment.
D)None of the answer options is correct.

Question 34

Researchers have noted that children who learn to play a musical instrument through taking lessons have higher average SAT scores, higher average GPAs, and higher average class ranks. This is an example of:

A)an experiment.
B)an observational study.
C)the establishing of a causal relationship through correlation.
D)a block design, with music and no-music groups as blocks.

Question 35

A nutritionist has designed an intervention to motivate parents of preschool children to provide more fruits and vegetables to their children. To study the effectiveness of this intervention, the nutritionist will conduct an experiment in which half of the selected study participants will receive the intervention and the others will not. Study subjects will be recruited from families with children who receive medical care for their children through the university health center. The nutritionist will compare the amount of fruit consumed per day by the children in families who received the intervention and by those who did not. Which of the following is true?

A)The amount of fruit consumed is the treatment.
B)The amount of fruit consumed is the factor.
C)The amount of fruit consumed is the response.
D)The amount consumed is the carryover effect from before and after the intervention.

Question 36

Will a fluoride mouthwash used after brushing reduce cavities? Twenty sets of twins were used to investigate this question. One member of each set of twins used the mouthwash after brushing, and the other did not. After six months, the difference in the number of cavities for those using the mouthwash was compared with the number of cavities for those who did not use the mouthwash. This experiment uses:

A)random placeboes.
B)double blinding.
C)double replication.
D)a matched pairs design.

Question 37

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. Before the start of the class, each student is asked about the number of hours slept the previous night. Each student's eye movement is then tracked throughout the lecture. The amount of time is recorded whenever the student is not focused on either the instructor or taking notes. This is an example of:

A)an observational study.
B)a sample survey.
C)a randomized experiment.
D)a matched pairs study.

Question 38

One hundred sixty people who suffer from painful diabetic neuropathy have volunteered to participate in a study. Eighty are selected at random and are given the drug gabapentin, which (although originally intended to prevent epileptic seizures) has properties that may make it useful to alleviate neuropathy. The remaining participants are given a placebo. A neurologist evaluates the symptoms of all volunteers after two months to determine if there has been substantial improvement in the severity of the symptoms. This study would be double-blind if:

A)neither drug had any identifying marks on it.
B)neither the volunteers nor the neurologist were allowed to see each other during the session in which the neurologist evaluated the severity of the symptoms.
C)neither the volunteers nor the neurologist knew which subjects had received the drug and which had received the placebo.
D)All of the answer options are correct.

Question 39

Medical researchers are excited about a new cancer treatment that destroys tumors by cutting off their blood supply. To date, the treatment has only been used on mice, but in mice it has been nearly 100% effective in eradicating tumors and appears to have no side effects. As evidence of the effectiveness of the new treatment in treating cancer in humans, these studies:

A)display a high degree of statistical significance, and so the treatment will work in humans with nearly 100% certainty.
B)are convincing, assuming the results have been replicated in a large number of mice.
C)are convincing, assuming that proper randomization and control were used.
D)suffer from lack of realism.

Question 40

A study attempts to compare two sunscreens. Each of 50 subjects with varying skin complexions will use both sunscreens-Screen A on one side of the body and Screen B on the other side. For each subject, a coin is tossed to determine which side receives Screen A and which receives Screen B. Researchers measure the amount of ultraviolet light exposure over both treated areas for each subject. This is an example of:

A)a matched pairs experiment.
B)a double-blind observational study.
C)a stratified analysis.
D)the placebo effect.

Question 41

An insurance underwriter wonders whether sports cars "cause" people to drive too fast or whether those with a propensity for speeding are drawn to sports cars. She secures some research funds and recruits 100 car buyers to her study. She randomly assigns 25 drivers to each of four groups: 1) sports car white, 2) sports car red, 3) sedan white, and 4) sedan red. The primary research questions are: 1) Do sports cars make people drive faster? and 2) Does color make a difference? The underwriter finds that drivers of red sports cars are the fastest, followed by drivers of red sedans. Her conclusion is that:

A)driving a sports car makes people drive fast.
B)driving a red sports car makes people drive fast.
C)driving a red car makes people drive fast.
D)All of the answer options are correct.

Question 42

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. After consultation with a statistician, the educator decides to randomly allocate students to either a group that will sleep for 8 hours the night before class or 6 hours. The educator does not know which group a student belongs to when she or he comes to class. The educator, after talking to some students and before the experiment, decides that the number of classes students have on the same day before calculus could potentially confound the study and wishes to make an adjustment. The design that allows for such an adjustment is called:

A)a randomized block design.
B)a placebo controlled completely randomized design.
C)a double-blinded design.
D)a matched block design.

Question 43

An insurance underwriter wonders whether sports cars "cause" people to drive too fast or whether those with a propensity for speeding are drawn to sports cars. She secures some research funds and recruits 100 car buyers to her study. She randomly assigns 25 drivers to each of four groups: 1) sports car white, 2) sports car red, 3) sedan white, or 4) sedan red. The primary research questions are: 1) Do sports cars make people drive faster? and 2) Does color make a difference? This study has:

A)four treatments.
B)two treatments.
C)four treatments and a placebo.
D)two treatments and a placebo.

Question 44

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. Before the start of the class, each student is asked about the number of hours slept the previous night. Each student's eye movement is then tracked throughout the lecture. The amount of time is recorded whenever the student is not focused on either the instructor or taking notes. The class is held at 11 A.M. and the instructor also asks questions about prior classes that day. The response variable is:

A)the number of hours slept the night before.
B)the amount of time not focused.
C)the time of day the class is given.
D)the number of prior classes that day.

Question 45

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. After consultation with a statistician, the educator decides to randomly allocate students to either a group that will sleep for 8 hours the night before class or 6 hours. The educator does not know which group a student belongs to when she or he comes to class. The study subjects are:

A)the groups assigned to sleeping either 6 or 8 hours.
B)the students participating in the experiment.
C)the students who do not fall asleep in class.
D)the students who are enrolled in any of the calculus classes.

Question 46

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. The educator has contacted a statistician to help plan a proper study for the assessment of cause and effect. The type of study required is called:

A)a replicated observational study.
B)a quasi-experiment.
C)a completely randomized design.
D)a blocked study.

Question 47

An insurance underwriter wonders whether sports cars "cause" people to drive too fast or whether those with a propensity for speeding are drawn to sports cars. She secures some research funds and recruits 100 car buyers to her study. She randomly assigns 25 drivers to each of four groups: 1) sports car white, 2) sports car red, 3) sedan white, and 4) sedan red. The primary research questions are: 1) Do sports cars make people drive faster? and 2) Does color make a difference? The result shows that people driving red cars drive faster than those driving white cars. There is no statistically significant difference by type. This conclusion is:

A)wrong, because the stated purpose was to study type, not color.
B)valid, because this was a randomized study and drivers were randomized on color and type.
C)wrong, because you cannot study two different things, like type and color, at once.
D)valid, because sports cars obviously make people drive fast.

Question 48

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. After consultation with a statistician, the educator decides to randomly allocate students to either a group that will sleep for 8 hours the night before class or 6 hours. The educator does not know which group a student belongs to when she or he comes to class. This study is:

A)double blinded, because the educator does not know who belongs to the 6- or 8-hour group.
B)double blinded, because the students have been told not to inform the educator about the treatment group they belong to.
C)a placebo controlled study, because 8 hours is normal sleeping time.
D)a single blinded randomized study, because the educator does not know the treatment groups students belong to but the students know.

Question 49

An insurance underwriter wonders whether sports cars "cause" people to drive too fast or whether those with a propensity for speeding are drawn to sports cars. She secures some research funds and recruits 100 car buyers to her study. She randomly assigns 25 drivers to each of four groups: 1) sports car white, 2) sports car red, 3) sedan white, and 4) sedan red. The primary research questions are: 1) Do sports cars make people drive faster? and 2) Does color make a difference? The underwriter worries that gender affects driving behavior and thinks it may actually be a confounder. She decides to randomize males and females separately. This is a:

A)randomized study with one factor and two blocking variables.
B)randomized study with two factors and one blocking variable.
C)randomized study with three factors.
D)None of the answer options is correct.

Question 50

An educator wishes to study the effects of sleep deprivation on the ability to concentrate. He decides to study the students in a calculus class. Each student enrolled in the class is randomly assigned to either sleeping 6 or 8 hours the night before. Each student's eye movement is then tracked throughout the lecture. The amount of time is recorded whenever the student is not focused on either the instructor or taking notes. This study has:

A)one factor and one treatment.
B)two factors and one treatment.
C)one factor and two treatments.
D)two factors and two treatments.